Magnetic core matrix arrangement employing readout from selected nonmagnetized cores



Nov. 16, 1965 J K. A. OLSSON 3,218,634

MAGNETIC CORE MATRIIX ARRANGEMENT EMPLOYING READOUT FROM SELECTED NON-MAGNETIZED CORES Filed June 27. 1960 H j/v VE/VT'OR J'o/vs A z/Rr 62 was 04:50

United States Patent 3,218,634 MAGNETIC CORE MATRIX ARRANGEMENT EM- PLOYING READOUT FROM SELECTED NON- MAGNETIZED CORES Jiins Kurt Alvar Olsson, Tullinge, Sweden, assignor to Telefonaktiebolaget L M Ericsson, Stockholm, Sweden, a corporation of Sweden Filed June 27, 1960, Ser. No. 38,914 Claims priority, application Sweden, Apr. 13, 1960, 3,692/60 6 Claims. (Cl. 340-348) The present invention relates to a number-sending de vice for calling frequently wanted subscribers to a telephone system.

It is known in Sweden to obtain a subscribers numberrepresenting signal, using mechanical arrangements, by the operation of one button of a number of buttons in a set. The mechanical construction of such arrangements has been rather complicated and bulky, and also it has not been as easy as could be desired to change a fixed subscribers number set up in such an arrangement.

According to the present invention there is provided a number-sending device for calling frequently wanted subscribers to a telephone system, wherein there is generated in response to the operation of a button or a key a subscribers number-representing signal com-posed of a plurality of partial signals each of which represents a character of the subscriber number, the number-sending device comprising a storage matrix of magnetic cores, each of which cores is provided with a first winding, the first windings of all the cores in each row along one axis of the matrix being connected together for simultaneous energization, the states of the cores in each row representing a character stored in that row, and there being a respective contact actuated by means of said button or key associated with each of said rows, one side of which contact is connected to the first windings of that row, and each of which cores is provided with a second winding, the second windings of all the cores in each row along the other axis of the matrix being connected together, the device further comprising a chain of successively operated connecting stages, there being a stage associated with each row along said one axis, the operation of any one of said stages causing the other side of the contact associated with the corresponding row to be connected to a pulse-generating means, a signal-generating means connected to said second windings of the cores in each row along the other :axis of the matrix, which signal-generating means provides a partial signal as each row of cores along said one axis of the matrix is fed through its respective contact from said pulse-generating means as said chain of successively operated connecting stages operates, the characteristic of each partial signal generated depending on the states of the cores in that row which is being fed from said pulse-generating means and thus upon the character stored therein.

For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawing, in which the figure shows a schematic circuit of a number-sending device.

The number-sending device shown in the figure is equipped with a set of thirty buttons, two of which are shown in the drawing and represented by K and M. For each button, for instance, the button K, there are provided a number of contacts k1, k2 k6, which are actuated simultaneously by operation of the button K, and there is associated with the button K a ferromag netic memory arrangement in the form of a storage matrix of magnetic cores so arranged that the reading out of information stored in the matrix does not cause erasure of that stored information. In the matrix, the rows of cores along the horizontal axis as shown in the figure will be hereinafter called the rows, and the rows of cores along the vertical axis will be called the columns. Each core is provided with a first winding (reading winding), and the first windings of a row of cores in the matrix are connected in series to one side of a respective contact of the contacts k1 to k6. The cores in the matrix are also provided each with a second winding (output winding), all the second windings of cores in one column being connected in series. The embodiment shown in the figure has eight cores for each of the contacts k1 to k6. The contact k2, for instance, is associated with the eight cores C21, C22 C28. The first windings of the cores C21 to C28 connected in series are shown as a horizontal conductor L21, one end of which is connected to one side of the contact k2. A column of series-connected second windings is schematically shown as a vertical conductor L8. These windings are wound on the cores C18, C28 C68 in the storage matrix associated with button K. The second windings on the cores in the storage matrix belonging to the button M, for example, Z918, Z128 I268, are connected in series with each other and the corresponding columns of the two matrices; for example, C18 to C68 and b18 to 1168 are also connected in series and to inputs of a signal-generating means G1, G2 G8 and F1, F2 F8, which means will be described later.

For the buttons K, M, and also for the other buttons of the arrangement, there is provided a chain of successively operated connecting stages H, 1, 2 6 and S containing a number of stages corresponding at least to the number of characters in the subscribers number, which chain steps stage by stage during the generation of the subscribers number-representing signal, there being a respective stage associated with each row of the matrix being used, so that operation of any one stage causes the connection of its associated contact of the contacts k1, k2 k6, in the case of the button K, to a common pulse-generating means 11. The connecting chain can be formed in a known way with a number of output conductors, one for each stage of the chain, which successively and during a short period of time are at a certain potential as the chain steps. These output conductors are connected to gates V1, V2 V6, which, when the associated output conductors are at said certain potential, are opened to allow pulses from the pulsegenerating means 11 to be applied to the respective contacts, such as k2. The successive stepping of the chain when writing in a subscribers number into a matrix of the number-selection arrangement can be seen on a lamp display LT, which display is connected to the stages of the chain. Two connections from the chain to the display LT are shown in the figure from the stages 1 and 6. Immediately before a button, for example K, is pressed, the connecting chain is in the position S. Upon pressing the button K, a further contact k7 is closed, as well as the contacts k1 to k6. The contact k7 is connected in an input circuit to a starting means 10 common to all the buttons, which starting means is arranged to give a starting impulse to the common pulsegenerating means 11, which thus commences generation, and also to the initial stage H of the connecting chain H, 1, 2 6. Consequently, the chain steps first from the position S (the rest position) to the position H (the initial position), and then as pulses'are applied to it, works stage by stage through all the stages 1 to 6, and then stops again in the position S. The stepping from position ,H to position S occurs as a result of trigger pulses from a further pulse generator PG, which provides pulses of one polarity and which is connected to all the stages 1 to 6 in the connecting chain through a make contact M81 and a gate VO opened by the starting means 10. Pulses from the pulse generator PG cause. the stepping of the stages upon reading out a stored subscribers number.

The signal-generating means G1 to G8 and F1 to F8 comprises eight signal generators G1 to G8, each of which provides an AC. output of a different frequency from the frequencies of the others. These generators are connected to a common output conductor L via the gates 21 to 28, respectively. The gates 21 to 28 are normally held closed to the AC. outputs of the generators G1 to G8, but a gate opens when a direct voltage from One of the amplifiers F1 to F8 is fed to the gate; that is, the gate 22 passes the AC. output of the gen erator G2 to the line L when a direct voltage is applied to it from the amplifier F2. Each of the amplifiers F1 to F8 is connected on the input side to one of the series connections of the previously mentioned second windings on the cores in the corresponding rows of the storage matrices. Consequently, the windings on the cores C18, C28 to C68 and M8, 1128 to 1768 are connected in series with each other (the vertical conductor L8) and to the input of the amplifier P8.

In order to put the cores in each storage matrix into the neutral or set-zero position, there is a device 12 which can be connected via a make contact 121 and a selector contact 122 to third windings provided on all the cores in each matrix, which third windings are all series connected. In the embodiment shown, the windings on all the cores in each column are series connected, and the columns are then series connected. The windings n the cores C11 to C18 are indicated by the conductor L2 in the matrix associated with the button K. With the contact 121 closed and the selector contact 122 in the position k, all the cores in the storage matrix associated with the button K, which matrix includes the mentioned cores C11, C15, C21, C22, C28 and C68, ar set to zero by simultaneous energization of the third windings by the device 12. This neutral or set-zero position occurs only with pulses from the device 12. This zero position will be called the magnetized state of the cores, as opposed to the demagnetized state to be described later.

For the demagnetizing of the cores in the storage matrices from the zero magnetized state there is provided a demagnetizing means 13 which is arranged to furnish a sinusoidal damped alternating voltage and which can be connected to one or more of a number of series connections of windings, comprising fourth windings (writing-in windings) on the cores, the fourth windings of the cores in one column of a matrix being connected in series and the corresponding columns in the matrices being also connected together. One column of the seriesconnected fourth windings of the matrix of th button K is represented by the conductor L5, which is in turn connected to the fourth windings of the corresponding column of the matrix of the button M. The series-connected columns of fourth windings are connected to the demagnetizing means 13 by operation of the keys J1 to 8.

The parts of the arrangement indicated by MS, LT, 12, 122, J1, J2 to J8 and 13 have been drawn over a broken line in the figure, while the remainder of the number-selection arrangement lies under said line. This has been done to indicate that the parts over the line can suitably be built together to form one unit, which can be plugged into another unit containing the parts shown under the line. This method of making the numbersending apparatu in units makes it possible for the upper unit containing those parts shown above the line to be common, for instance, to a number of telephone instruments in one room, each instrument having its own number-sending device.

The circuit and the component parts of a numbersending device having been described, the operation thereof will now be explained.

When a subscriber wants to introduce an often called subscribers number into his number-sending device, he plugs said upper unit, which makes it possible to perform writing in, into th lower unit containing the buttons and matrices, etc. and switches off the contact MS1 so that the pulse generator PG is disconnected. Then he presses the appropriate button K, M of the ferromagnetic memory in which he will write in and store the subscribers number. If, for example, he presses down the button K, the starting means 10 causes th chain H to S to step directly from S to H and the pulse-generating means 11 to furnish pulses.

All the cores of the storage matirx of the ferro-magnetic memory arrangement associated with the button K need first to be set at zero. This is done by setting the selector contact 122 in the position k and then closing the contact 121. Pulses from the device 12 put all the cores in the matrix into the magnetized state; that is, they are set at zero.

The writing in of the subscribers name now occurs digit by digit. As the chain of successively operated connecting stages has six working stages (1 6), a sixfigure subscriber number can be written in. The number value of each digit in the number is translated into a code, and the cores in the row of the matrix which corresponds to this digit are given conditions of mag netization in accordance with this code. If, for instance, the subscribers number 123 456 is to be written in, the code can be so arranged that 1 corresponds to XIIIXIII, where X is a demagnetized core and I is a magnetized core in the row. The digit 2 corresponds to XIIIIXII, 3 corresponds to XIIIIIXI, and so on. When the first digit of the subscribers number with the number value 1 is to be written in, the chain HS is stepped forward to the stage 1 by pressing down the control button MS. A glowing lamp farthest to the left in the lamp display LT shows that the stage 1 of the chain is now operated. The gate VI is therefore opened, and pulses from the pulsegenerating means 11 are fed to all the cores in the row of the matrix associated with the contact k1. The amplitude of the alternative positive and negative pulses from the pulse generator 11 is 1m, and this amplitude is less than that which is required to change the magnetizing condition of any core. This means that the cores of the row being fed with pulses are not influenced by the pulses from the pulse generator 11, and consequently they remain in the magnetized state. The number value 1 is written in by pressing down the buttons J1 and J5. The cores C11 and C15 are then influenced by the pulses of the pulse generator 11 as well as by the damped alternating current from the demagnetizing means 13; this alternating current has a maximum amplitude equal to Im. The value Im is so chosen that 2Im exceeds what corresponds to the coercive force of the cores magnetized by the device 12. This means that the two cores C11 and C15 in the same upper row of the matrix are now in a substantially demagnetized stage as compared with the magnetized (set at zero) cores.

The first digit having been written in, the second digit of the subscribers number, with the number value in this case equal to 2, is then written in in the second row of cores C21 to C28. To do this the chain HS is stepped forward to the stage 2 by again pressing the button MS. A glowing lamp next to last at the left of the lamp display LT shows that stage 2 of the chain is now operated. The gate V2 is thus opened and allows pulses from the pulse-generating means 11 to be fed to the first windings of the cores, represented by L21, associated with the contact k2. The pulses are fed through the closed contact k2, and the number value 2 is Written in by pressing down the buttons J1 and J6, the changing of the states of the cores being as above described. In this way each digit is written in until the whole subscribers number is stored in the matrix. Other subscribers numbers may be stored in the number-sending device by preparing other matrices in the same Way as has been described for the matrix associated with the button K.

When a calling subscriber makes use of the described arrangement, the following occurs. If he calls a subscriber whose numebr is stored, for instance, in the matrix associated with the button M, when he presses button M the starting means emits a starting impulse to the pulse generator 11 and a starting impulse to the position H, and opens the gate V0. The first pulse from PG steps the chain H-S to step 1, which opens the gate V1. Pulses from the generator 11 can now pass V1 to the row of cores at the top of the memory (with cores I118, I228 Z168) belonging to the button M. Pulses are transmitted to the amplifiers F1, F2 F8 in accordance with a code corresponding to the first digit of the desired number, which digit previously was written in the memory circuit. These code pulses open corresponding gates of the gates 21, 22 28 so that alternating current signals can be transmitted to the line L from the generators G1, G2 G8, which signals together represent the said first digit. The second pulse from PG stesp the chain H-S to the step 2, which opens the gate V2, and so on. In this way alternating current signals are generated representing all the digits of the desired number. Thus, the cores which are still set at zero do not give rise to output signals in the series connections (L8) of the second windings thereon which are connected to the amplifiers F1 to F8, because the amplitude of these pulses is below the level required to overcome the coercive force of the cores which are set at zero. There are signals obtained from the demagnetized cores in response to the pulses, which signals are fed to the appropriate amplifiers F1 to F8, where they are rectified and amplified. The direct voltage outputs are fed to the corresponding gates of the gates 21 to 28 which are opened and let alternating currents pass from the corresponding signal generator of the signal generators G1 to G8 to the line L. In the foregoing example, with the subscribers number 123 456, the condition of the cores for the second digit of the number was symbolized by XIIIIXII; the magnetized cores C22, C23, C24, C25, C27 and C28, which are set at zero, will not give rise to any output signals, but the remaining two cores C21 and C26 of the row do so. Consequently, there appears on the line L a partial signal representing the digit 2, which partial signal is characterized by the fact that it contains the two frequencies of the generators G1 and G6. Together with five other partial signals from the other rows of the matrix, this partial signal forms the required subscribers number-representing signal.

In the storage matrices which have ben described this arrangement is such that the application of the reading pulses to the cores in order to release the stored information does not erase the stored information, and hence rewriting in of a subscribers number is not necessary after reading out.

I claim:

1. Apparatus for generating a coded combination of signals comprising a plurality of magnetizable cores, means for initially magnetizing each of said cores to a given state of magnetization, means for selectively demagnetizing selected cores of said plurality of cores magnetized to a given state of magnetization, means for exciting each of said cores with pulses of alternate magnetization of an amplitude insufiicient to overcome the coercive forces of any magnetized core but suflicient to cause an alternating magnetization in the selected demagnetized cores, and signal output means coupled to each of said cores for generating signals in response to the alternating magnetization.

2. Apparatus for generating a sequence of numbers,

each of said numbers being represented by a coded combination of signals comprising a storage matrix of magnetic cores arrayed in rows and columns, a common winding inductively coupled to every core of said matrix, a plurality of row windings, each of said row windings being inductively coupled to all the magnetic cores in one row of cores, respectively, a plurality of column windings, each of said column windings being inductivety coupled to all of the magnetic cores in one column of cores, respectively, a plurality of output windings, each of said output windings being inductively coupled to all of the magnetic cores in one of said columns, respectively, unidirectional current pulse-generating means selectively connectible to said common winding for generating a unidirectional current pulse of sufficient amplitude to magnetize all of said magnetic cores to a given state of residual magnetization with a given coercive force, alternate polarity current pulse-generating means for generating a current pulse of a first polarity followed by a current pulse of a second polarity, connecting means for connecting said alternate polarity current pulse-generating means sequentially to said row windings, damped alternating current-generating means, selective connecting means for connecting said damped alternating current-generating means to selected ones of said column windings, the amplitude of the damped alternating current and the amplitude of alternate polarity current pulses being such that any magnetic core, previously magnetized to said residual state of magnetization, which is coincidentally influenced by current in the row and column windings inductively coupled thereto, is substantially demagnetized, whereas the amplitude of the alternate polarity current pulses in said row windings, in the absence of damped alternating current pulses in said column windings, induces an alternating magnetization in the magnetic cores inductively coupled to the row windings receiving the alternate polarity current pulses and is ineffective substantially to overcome the coercive force and change the state of magnetization of the magnetized cores so that, after selected ones of said magnetic cores have been demagnetized, each time said row windings are sequentially connected to said alternate polarity current pulse source a sequential plu rality of parallel coded combinations of signals are present on said output windings, each parallel coded combination representing the states of magnetization of the magnetic cores in a row.

3. The apparatus of claim 2, wherein said connecting means includes a plurality of gating means each including a signal output, a signal input and a control input, each of said gating means transmitting from its output the signal present at its input only when a control signal is present at its control input, means for connecting the signal output of each gating means to one of said row windings, respectively, means for connecting all the signal inputs of all of said gating means to said alternate polarity current pulse source, a chain of successively operating stages wherein only one stage operates at a time and the stages successively operate in response to stepping pulses, each stepping pulse causing the succeeding stage to operate and transmit a control signal, and means for connecting each stage to the control input of one of said gating means.

4. The apparatus of claim 3, further comprising successively operable means for generating a single pulse at a time, sequential pulse-generating means for generating a sequence of pulses and switching means for selectively connecting said successively operable means and said sequential pulse-generating means to said chain of stages.

5. The apparatus of claim 2, further comprising a plurality of gating means, each of said gating means including a signal input, a signal output and a control input, each of said gating means transmitting from its signal output a signal present at its signal input only when a control signal is present at its control input, a plurality of tone signal generators, means for connecting each tone signal generator to the signal input of one of said gating means, respectively, and means for connecting each of said output windings to the control input of one of said gating means, respectively.

6. Apparatus for storing a plurality of numbers represented by coded combinations of states of magnetization, comprising a storage matrix of magnetic cores arrayed in rows and columns, a common winding inductively coupled to every core of said matrix, a plurality of row windings, each of said row windings being inductively coupled to all the magnetic cores in one row of cores, respectively, a plurality of column windings, each of said column windings being inductively coupled to all of the magnetic cores in one column of cores, respectively, unidirectional current pulse-generating means selectively connectible to said common winding for generating a unidirectional current pulse of sufiicient amplitude to magnetize all of said magnetic cores to a given state of residual magnetization, alternating polarity current pulse-generating means for generating a current pulse of a first polarity followed by a current pulse of a second polarity, connecting means for connecting said alternating polarity current pulse-generating means sequentially to said row windings, damped alternating current-generating means, selective connecting means for connecting said damped alternating current-generating means to selected ones of said column windings, the amplitude of the damped al- 8 ternating current and the amplitude of the alternate polarity current pulses being such that any magnetic core, previously magnetized to said residual state of magnetization, which is coincidentally influenced by current in the row and column windings inductively coupled thereto, is substantially demagnetized.

References Cited by the Examiner UNITED STATES PATENTS 2,499,606 3/1950 Parkinson 179-902 2,594,325 4/1952 Lovell 179--90.2 2,708,267 5/1955 Weidenhammer 340-166 2,861,130 11/1958 Yanagida 17990.2 2,880,278 3/1959 Vandenberg 179-902 2,904,636 9/1959 McKim et a1. 17990.3 2,992,416 7/1961 Sims 340174 3,008,128 11/1961 Powell 340166 3,015,813 1/1962 Tyrlick 340166 3,048,827 8/1962 Wright et a1 340-174 3,052,872 9/1962 Hanewinkel 340--166 3,069,658 12/1962 Krmaskoy 340-166 3,074,059 1/1963 Flavan 179-90.2 3,134,967 5/1964 Ringer 340- 166 3,144,640 11/1964 Grooteboer 340-166 NEIL C. READ, Primary Examiner.

L. MILLER ANDRUS, Examiner. 

1. APPARATUS FOR GENERATING A CODED COMBINATION OF SIGNALS COMPRISING A PLURALITY OF MAGNETIZABLE CORES, MEANS FOR INITIALLY MAGNETIZING EACH OF SAID CORES TO A GIVEN STATE OF MAGNETIZATION, MEANS FOR SELECTIVELY DEMAGNETIZING SELECTED CORES OF SAID PLURALITY OF CORES MAGNETIZED TO A GIVEN STATE OF MAGNETIZATION, MEANS FOR EXCITING EACH OF SAID CORES WITH PULSES OF ALTERNATE MAGNETIZATION OF AN AMPLITUDE INSUFFICIENT TO OVERCOME THE COERCIVE FORCES OF ANY MAGNETIZED CORE BUT SUFFICIENT TO CAUSE AN ALTERNATING MAGNETIZATION IN THE SELECTED DEMAG- 